Apache commons fileupload文件上传实例讲解

Apache commons fileupload文件上传实例讲解

文件上传的方法主要目前有两个常用的，一个是SmartUpload，一个是Apache的Commons fileupload.

我们这里主要介绍下第二个的用法，首先要上传文件，注意几个问题：

1 form表单内，要添加空间

2 form表单的内容格式要定义成multipart/form-data格式

3 需要类库：1 commons-io.jar 2commons-fileupload-1.3.1.jar

接下来我们看下用法。

首先阅读Apache commons fileupload的官方文档可以发现下面几个常用的函数：

1 创建文件解析对象

复制代码 代码如下:

DiskFileUpload diskFileUpload = new DiskFileUpload();

2 进行文件解析后放在List中，因为这个类库支持多个文件上传，因此把结果会存在List中。

复制代码 代码如下:

List list = diskFileUpload.parseRequest(request);

3 获取上传文件，进行分析（不是必须）

复制代码 代码如下:

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

4 创建新对象，进行流拷贝

file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());

file1.getParentFile().mkdirs();

file1.createNewFile();

InputStream ins = fileItem.getInputStream();

OutputStream ous = new FileOutputStream(file1);

try{

byte[] buffer = new byte[1024];

int len = 0;

while((len = ins.read(buffer)) > -1)

ous.write(buffer,0,len);

out.println("以保存文件"+file1.getAbsolutePath()+"
");

}finally{

ous.close();

ins.close();

}

这样我们就完成了文件的上传。

fileUpload.html

上传文件

web.xml

UploadServlet

com.test.hello.UploadServlet

UploadServlet

/servlet/UploadServlet

UploadServlet.java

package com.test.hello;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.PrintWriter;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.DiskFileUpload;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileUploadException;

public class UploadServlet extends HttpServlet {

/**

* Constructor of the object.

*/

public UploadServlet() {

super();

}

/**

* Destruction of the servlet.

*/

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

// Put your code here

}

/**

* The doGet method of the servlet.

*

* This method is called when a form has its tag value method equals to get.

*

* @param request the request send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setCharacterEncoding("UTF-8");

response.getWriter().println("请以POST方式上传文件");

}

/**

* The doPost method of the servlet.

*

* This method is called when a form has its tag value method equals to post.

*

* @param request the request http://send by the client to the server

* @param response the response send by the server to the client

* @throws ServletException if an error occurred

* @throws IOException if an error occurred

*/

@SuppressWarnings({ "unchecked", "deprecation" })

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

File file1 = null,file2=null;

String description1 = null,description2 = null;

response.setCharacterEncoding("UTF-8");

request.setCharacterEncoding("UTF-8");

response.setContentType("text/html");

PrintWriter out = response.getWriter();

DiskFileUpload diskFileUpload = new DiskFileUpload();

try{

List list = diskFileUpload.parseRequest(request);

out.println("遍历所有的FileItem...
");

for(FileItem fileItem : list){

if(fileItem.isFormField()){

if("description1".equals(fileItem.getFieldName())){

out.println("遍历到description1 ...
");

description1 = new String(fileItem.getString().getBytes(),"UTF-8");

}

if("description2".equals(fileItem.getFieldName())){

out.println("遍历到description2 ...
");

description2 = new String(fileItem.getString().getBytes(),"UTF-8");

}

}else{

if("file1".equals(fileItem.getFieldName())){

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

out.println("遍历到file1...
");

out.println("客户端文件位置："+remoteFile.getAbsolutePath()+"
");

file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());

file1.getParentFile().mkdirs();

file1.createNewFile();

InputStream ins = fileItem.getInputStream();

OutputStream ous = new FileOutputStream(file1);

try{

byte[] buffer = new byte[1024];

int len = 0;

while((len = ins.read(buffer)) > -1)

ous.write(buffer,0,len);

out.println("以保存文件"+file1.getAbsolutePath()+"
");

}finally{

ous.close();

ins.close();

}

}

if("file2".equals(fileItem.getFieldName())){

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

out.println("遍历到file2...
");

out.println("客户端文件位置："+remoteFile.getAbsolutePath()+"
");

file2 = new File(this.getServletContext().getRealPath("attachhttp://ment"),remoteFile.getName());

file2.getParentFile().mkdirs();

file2.createNewFile();

InputStream ins = fileItem.getInputStream();

OutputStream ous = new FileOutputStream(file2);

try{

byte[] buffer = new byte[1024];

int len = 0;

while((len = ins.read(buffer)) > -1)

ous.write(buffer,0,len);

out.println("以保存文件"+file2.getAbsolutePath()+"
");

}finally{

ous.close();

ins.close();

}

}

}

out.println("Request 解析完毕

");

}

}catch(FileUploadException e){}

out.println(" ");

out.println("");

out.println("

out.println("

if(file1 != null){

out.println("

out.println("

out.println("

out.println("

out.println("

}

if(file2 != null){

out.println("

out.println("

out.println("

out.println("

out.println("

}

out.println("

out.println("

out.println("

out.println(description1);

out.println("

out.println("

out.println("

out.println("

out.println("

out.println(description2);

out.println("

out.println("

out.println(" ");

out.println("");

out.flush();

out.close();

}

/**

* Initialization of the servlet.

*

* @throws ServletException if an error occurs

*/

public void init() throws ServletException {

// Put your code here

}

}

运行示例

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